The present invention relates to a system for heating fluid hose, and more particularly to a system for heating fluid hose in applications wherein one or more fluid components are delivered through the hose from a remote location to a point of application.
The invention is particularly adaptable for systems requiring close temperature control over liquid components such as multiple component coatings which are separately delivered to a point of application, and are mixed and applied from a common applicator or spray gun. Systems of this type generally require fairly precise control over the temperature of the delivered fluid, and the quality of coating application is dependent upon both the temperature of the liquid components and the temperature of the surface to which the components are mixed and applied. Such systems may be found in industrial plant installations, wherein the liquid temperature at the point of application is at least somewhat controllable by monitoring the industrial plant ambient temperature. However, such systems are also useful for coating applications in an outdoors environment. For example, such systems are utilized in the application of plural component urethane and other foam materials for the application of roof coatings on buildings. In this latter case, the coating application problem becomes complicated in a number of important respects. First, the components typically applied in such applications are generally quite temperature responsive and sensitive, and for optimum coating quality these temperatures should be closely controlled. Further, the quality of coating is significantly affected by the temperature of the surface which receives the coating, and in the case of building roofs may be higher than, but proportional to the ambient air temperature. Still further, the nature of a practical roof coating application requires that hose lenqths extend for considerable distances, and be very ruggedly constructed because of the physical abuse the equipment suffers in hauling it to the point of application. At the same time, the liquid materials flowing through the hoses must be kept at a constant temperature, within a fairly narrow range, in order to insure that the temperature of the liquid at the point of mixing and application of the fluids be reasonably well-defined. Because of the physical abuse that the hoses tend to take over use, it is very difficult to construct an intricate temperature sensing mechanism into the hose itself. Further, because of the widely ranging requirements for conveying the liquids over greater or shorter distances, it is convenient to provide such hose in sections, in convenient lengths of twenty-five or fifty feet. Thus, hose couplers must be provided at both ends of each extension length, capable of connecting all of the liquid, air, and electrical circuits together reliably. If hose extension lengths must also carry temperature sensing circuits, electrical connections for these circuits must also be provided and such circuits must be ruggedly packaged in each extension length of hose.
There is a need for a system for delivering heated liquid through extended hose lengths, wherein the hose is heated to carefully control the temperature of the liquid being delivered, and wherein the temperature control and monitoring system may be safely contained to reliably operate under adverse environmental conditions. Further, there is a need for a heated hose temperature control system which takes into account the ambient temperature conditions at or near the point of application in adjusting the liquid temperature being delivered to the point of application. It is a principal object of the present invention to provide a system meeting these needs to enable liquid coatings to be applied under optimum application conditions.